PROJECT SUMMARY/ABSTRACT Hispanics are less likely to meet physical activity guidelines and those with osteoarthritis are more likely to report greater joint pain, functional limitations, and work limitations than non-Hispanic Whites. Among Hispanics, social and cultural factors are important intervention considerations because of the value placed on interdependence over independence in traditional Hispanic culture. It is hypothesized that culturally sensitive PA interventions designed for Hispanics offer potential to reduce disparities in physical activity and therefore OA symptoms. This study will adapt the self-administered 6-week walking intervention for Hispanics with osteoarthritis, Camine con Gusto (Walk with Ease) for dyads consisting of Hispanics with osteoarthritis and a member of their social network who supports their physical activity attempts (?supporter?). Developing a dyadic physical activity intervention shaped by the cultural value of interdependence will engage Hispanics with osteoarthritis and their supporters equally, thus positively influencing each other?s physical activity and providing greater osteoarthritis symptom relief. Two aims will achieve the overall goals of the proposed study: 1) Develop four candidate dyadic components targeting PA and OA symptoms; and 2) Determine the initial efficacy of the components using a randomized pre-post pilot study. Under the first aim, four dyadic intervention components will be developed with the input from a stakeholder panel and guidance from the mentoring team. Five intervention conditions will be tested for acceptability and feasibility of implementation (N= 10 dyads per condition). Four conditions will include one of the candidate components + Camine con Gusto and the fifth condition will include all candidate components + Camine con Gusto. Based on qualitative and quantitative assessments and stakeholder panel feedback, the four dyadic intervention components will be revised in preparation for Aim 2. Under the second aim, a randomized factorial design will be implemented to determine the initial efficacy of the dyadic intervention components on the daily steps of Hispanics with osteoarthritis. The factorial design will pilot test conditions consisting of different combinations of the components that when added to Camine con Gusto demonstrate initial efficacy in daily steps over six weeks. This aim will also allow for the examination of the reciprocating influences between Hispanics with osteoarthritis and their physical activity supporters on each other?s daily steps using dyadic analysis (actor-partner interdependence model). The proposed study will address several limitations of previous interventions by a) focusing on Hispanics with osteoarthritis, and b) examining an array of dyadic components separately to determine those components that should be retained in a future trial. Findings will inform a randomized controlled trial via a future R01 to evaluate the efficacy of the optimized dyadic intervention package containing only ?active? components.